Land Surveying Units and Resources

According to the American Congress on Surveying and Mapping, land surveying “is the science and art of making all essential measurements to determine the relative position of points…” In short, land surveying is the process of measuring and calculating the position of points in relation to each other for use in developing maps or establishing specific land boundaries. A person or government would use a land surveyor to determine exactly where property lines fall to establish ownership or determine governmental districts. Land surveyors also assist with creating road maps, topographical maps, and other scientifically precise maps using complex mathematical calculations and high-tech equipment. Today's land surveying uses satellite imaging and GPS, tools unimaginable to early surveyors.

Units of Measure

Acre – An acre is a measurement used in America and Great Britian, equivalent to 43,560 square feet. Using old measurements, it is equal to 10 square chains or 160 square poles. In Scotland and Ireland, an acre is equal to 1.27 and 1.6 English acres, respectively. The measurement of an acre began as a reference to a plowing area that was 4 poles wide by 40 poles (a furlong) long. A square mile spans 640 acres.

Arpent – French measurement for both length and area. (Also used in Canada and Louisiana.) In terms of length, an arpent is 191.8 feet. In terms of area, an arpent equals .845 acres approximately. An arpent is the same as 36,802 square feet.

Chain – Measurement of length. Depending on locale, it may refer to a Rathbone chain, but most common reference is to a Gunter chain. A metal chain used by surveyors consisting of 100 links.

Colpa – Measurement of land used in Old Ireland. Generally understood to be one acre of good Irish land, although the area may be more, as the true understanding is the amount of land it takes to feed a horse or cow for a year’s time.

Furlong – Length measurement equal to 220 yards or 660 feet (40 poles.) Originally called a “furrow long” which was the length of a furrow plowed by an team of oxen in a single pass. (See also Gunter’s Chain.)

Gunter’s Chain – Length measurement equivalent to 66 feet. Invented in the 1600’s by Edmund Gunter, it became the standard measuring chain in surveying. The original Gunter’s chain measured 22 yards and equaled a tenth of a furlong. An acre equals 1 chain wide by 10 chains long. Queen Elizabeth I, in 1695 redefined the measurement of a mile from 5,000 feet to 5,280 feet so as to equal an even number of furlongs. One mile is the same as 80 chains.

Hectare – Area measurement using the metric system. A hectare is 10,000 square meters. In English measurements, that equals 107,639 square feet (2.471 acres.)

Hide – Area measurement used historically in England. The specific measurement varied from region to region, and was dependant on land conditions in the area. In short, it was the amount of land needed by a family to survive. In 1066, after the Norman conquest, it was standardized to 120 acres.

Labor – Texas and Mexico use this area measurement equal to 177.14 acres or 1 million square varas.

League – Also known as a legua, as an area measurement used in the Southwestern United Sates it equals 25 labors or 4428 to 4439 acres, depending on the state. As a measurement of length it equals roughly 3 miles.

Link – 1/100th of a chain, length is roughly equal to 7.92 inches.

Morgen – Taking it’s name from the German word, morgen (meaning morning) and representing the area that could be plowed in a morning’s time, this measurement of area equals approximately 06309 acres. It was used in Germany, Holland, and South Africa.

Out – When using chains to measure land, carriers staked the end of a chain before moving it and placing a stake at the new end. When ten stakes had been staked, a carrier was “out” of stakes, therefore an area of 10 chains became known as an out.

Perch – cross-reference with Pole.

Point – A system of reference for surveyors using compass points. The four main compass points, North, South, East, and West are subdivided into points of 11.25 degrees each. This allowed for descriptions such as north, northeast. More precise points are divided again by halves or quarters to provide detailed descriptions such as “SE by South, one quarter point South.” The descriptor “and by” means half a point in some areas.

Pole – A unit of measure used to describe both area and length. Other names include perch and rod. When used to measure length, a pole equals 16.5 feet. When used to measure area, a pole equals a square area 1 pole by 1 pole. A mile is 320 poles long. 160 square poles make up 1 acre. In measuring acreage, the acreage is sometimes given like this: 87 acres, 112 poles, which is the same as saying 87 and 112/160 acres.

Pueblo – In Spanish terms, a pueblo was a land grant under 1000 acres.

Rancho – In Spanish terms, a land grant over 1000 acres.

Rathbone’s Chain – Like a Gunter’s Chain, a Rathbone chain was used to measure land. A Rathbone Chain is 33 feet long or 2 poles.

Rod – Another term for pole.

Rood – Area measurement encompassing ¼ acre.

Toise – French measurement for length that is the equivalent of 6.4 feet. In traditional France, this would have been 6 pieds (French feet.)

Vara – Length measurement used by the Spanish (also known as the Spanish yard) and in the southwestern United States. A vara equals 33 inches, approximately. It varies depending on area, with states such as Texas standardizing a vara to 33 1/3 in the 1900’s.

Virgate – Used in Old English times to measure area, a virgate was the equivalent of one forth of a hide. One person could be supported on a virgate.